USG always recommends shot blasting, sand blasting, or scarifying a floor prior to installations of our self-leveling products. To decide whether mechanical preparation of substrate is required or not, the concrete substrate must be thoroughly assessed for its quality and tensile strength over the entire pour area. The assessment of concrete tensile strength must be made in its existing state without the removal of any foreign material that may be present on the concrete surface. Simple visual appearance of concrete substrate as strong and solid does not necessarily guarantee that the concrete substrate is free of impurities and has the right tensile strength.
A weak or degraded concrete surface layer must be removed mechanically to provide a solid base. Concrete exhibiting signs of laitance (a layer of weak material on the concrete surface either visible or invisible), scaling, spalling, crumbling or delamination must be mechanically removed to achieve a solid and clean substrate. Prior to installation of the underlayment, mechanically profile concrete subfloor to a minimum of CSP 3, in accordance with the industry standards as outlined in International Concrete Repair Institute (ICRI) Technical Guideline No. 310.2 Selecting and Specifying Concrete Surface Preparation for Sealers, Coatings, and Polymer Overlays.
Use mechanical removal methods such as shot blasting, scarifying or diamond grinding to clean and prepare the concrete subfloor contaminated with adhesives, asphalt or oil. Shot-blasting is the preferred method of mechanically profiling and preparing the concrete subfloor for the application of USG self-leveling underlayments.